Critically Evaluated Data
Objectives: to measure, calculate, critically compile, and disseminate reference data on atomic properties and fundamental constants in support of basic research, commercial development, and national priorities.
Intended Outcomes and Background
The intended outcome for this topic area is to maintain NIST as the premier source for atomic data and related fundamental constants.
NIST is recognized for its work in atomic data as the result of three principal efforts. The most prominent of these is the dissemination of critically-compiled data through databases on a publicly-accessible website. Examples of the most popular databases are the Fundamental Constants database and the Atomic Spectra database, but there are many other similar databases that address specific areas of high impact. The premier status of the NIST databases arises from the quality of data they contain.
Some of this data originates at NIST, but much of it has been gleaned from the open scientific literature. NIST adds considerable value through the process of critical compilation, a process of evaluating all known measurements and calculations for a particular parameter and selecting the best values based on predicted accuracy, as well as consistency with other related parameter values. The result of this effort is a suite of databases that receive more than 300,000 separate requests for data every month.
NIST’s reputation for atomic data is also based on a long history of excellent measurements by world-renowned staff using some of the most advanced equipment available. Existing work includes measurements of highly-charged ions with the NIST Electron Beam Ion Trap (EBIT), development of standard spectral sources for calibration of the next generation of space- and ground-based telescopes, and development of new measurement platforms for improved determination of fundamental constants.
Finally, NIST utilizes state-of-the-art numerical calculations to address needs for atomic data and improve fundamental constants. Work includes atomic structure calculations, studies of fundamental constants, and kinetic modeling of high-charged ions and high energy density plasmas.
Highlights and Accomplishments